Skilled machinists can predict intuitively trouble in workpiece for cutting by glancing at the machine part drawing. Such machining know-how gained through long experience may be regarded in a sense as the fuzzy object. In this paper, a rational way for the acquisition of and model representation of this know-how is discussed. The following became clear after the investigation : (1) Through an analysis of the fuzzy partial order relation among machine part drawings, the attributes of the machine part which show a tendency to develop cutting trouble were clarified. (2) By identifying machinist subjectivity with the fuzzy measure, the know-how of the trouble prediction could be represented by a structural model using the fuzzy integral.